1. Field of the Invention
The present invention relates generally to an apparatus and method for efficiently using antennas in a mobile communication terminal having wireless communication modules (such as Bluetooth) and Wireless Local Area Network (WLAN) modules, and in particular, to an apparatus and method for achieving antenna diversity and thus improving the reception sensitivity of Bluetooth and WLAN signals in a mobile communication terminal having Bluetooth and WLAN modules.
2. Description of the Related Art
Recent years have witnessed the proliferation of mobile communication terminals due to their portable convenience. The growing use of the mobile communication terminals has driven service providers and terminal manufacturers to develop terminals with additional and more convenient functions in order to attract more users.
Traditionally, mobile communication terminals support only Wireless Wide Area Network (WWAN) such as Code Division Multiple Access (CDMA) and Personal Communication Service (PCS). As they have recently been further equipped with more and convenient functions, WLAN and Wireless Personal Area Network (WPAN) systems including Institute of Electrical and Electronics Engineers (IEEE) 802/a/b/g, Bluetooth and Zigbee are added to the mobile communication terminals.
A WLAN transmits and receives over the air using radio frequency (RF) or light, thus ensuring user mobility and facilitating extension, repair and maintenance. Especially the IEEE 802.11 system offers a data rate of 11 Mbps in the 2.4 GHz band.
Bluetooth is a standard for short-range, low-cost radio links between electronic devices such as mobile personal computers (PCs) and mobile phones. It allows transfer of voice and data between digital devices without using cables. Bluetooth operates at 2.4 GHz, serving up to 1 Mbps in a range limited to 10 m.
FIG. 1 is a block diagram of a conventional mobile communication terminal having Bluetooth and WLAN modules. Referring to FIG. 1, a mobile communication terminal 100 includes a WWAN antenna 101, a communication module 107, a controller 109, a memory 111, a WLAN antenna 103, a WLAN module 113, a Bluetooth antenna 105, and a Bluetooth module 115. The communication module 107 covers all of 1st generation analog communications, 2nd generation CDMA, 2.5th generation PCS, and 3rd generation Code Division Multiple Access 2000 (CDMA2000).
The controller 109 provides overall control to the mobile communication terminal 100. For example, it processes and controls voice and data received from the communication module 107, the WLAN module 113, and the Bluetooth module 115.
The memory 111 includes a Read Only Memory (ROM), a Random Access Memory (RAM), and a flash ROM (not shown). The ROM stores the micro-codes of programs, needed for processing and controlling in the controller 109, and reference data. The RAM is a working memory of the controller 109, for temporarily storing data generated during execution of the programs. The flash ROM stores updatable data to be kept, such as a phone book and incoming/outgoing messages.
The WWAN antenna 101 transmits/receives RF signals in a band of 869 to 894 MHz in CDMA and in a band of 1930 to 1990 MHz in PCS. The communication module 107 processes RF signals received and transmitted through the WWAN antenna 101 according to a CDMA standard (e.g. IS-95).
When receiving an RF signal through the WWAN antenna 101, the communication module 107 downconverts the RF signal to a baseband signal and despreads and channel-decodes the baseband signal. For transmission, the communication module 107 spreads and channel-encodes transmission data, upconverts the coded data to an RF signal, and transmits the RF signal through the WWAN antenna 101.
The WLAN antenna 103 transmits/receives an RF signal in the 2.4 GHz band to/from an access point (AP) in the case of IEEE 802.11b. For reception, the WLAN module 113 downconverts an RF signal received through the WLAN antenna 103 to a baseband signal, converts the baseband signal to a digital signal through a low-pass filter (LPF) and an analog-to-digital (A/D) converter, and provides the digital data to the controller 109. For transmission, the WLAN module 113 modulates transmission data, converts the WLAN digital information to a baseband analog signal through a digital-to-analog (D/A) converter, upconverts the baseband analog signal to an RF signal, and transmits the RF signal through the WLAN antenna 103. The WLAN module 113 is so configured that transmission is enabled with reception disabled and reception is enabled with transmission disabled.
The Bluetooth antenna 105 transmits/receives an RF signal in the 2.4 GHz band at a data rate of 1 Mbps, for short-range radio communications at a low rate. The Bluetooth module 115 downconverts a received RF signal to a baseband signal, converts the analog signal to a digital signal, and provides the digital signal to the controller 109. It also converts transmission data to an analog signal, upconverts the analog signal to an RF signal, and transmits the RF signal through the Bluetooth antenna 105.
As described above, the WLAN module 113 and the Bluetooth module 15 operate in independent RF paths. Although they use the same 2.4 GHz Industrial Scientific Medical (ISM) band, both modules are so configured that their baseband units (not shown) exchange predetermined signals and correspondingly operate according to their priority levels in order to ensure coexistence between them.
If one of the WLAN and Bluetooth systems is used in the 2.4 GHz ISM band, the RF antenna of the other system becomes idle. Moreover, in the case of applying antenna diversity with the purpose of increasing the reception rates of the WLAN and Bluetooth systems, each system requires a plurality of antennas which occupy more area.